i.eb.hsebal01 - Computes sensible heat flux iteration SEBAL 01.

NAME  KEYWORDS  SYNOPSIS  Flags:  Parameters:  DESCRIPTION  NOTES  REFERENCES  SEE ALSO  AUTHOR  SOURCE CODE 

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NAME

i.eb.hsebal01 − Computes sensible heat flux iteration SEBAL 01.

KEYWORDS

imagery, energy balance, soil moisture, evaporative fraction, SEBAL

SYNOPSIS

i.eb.hsebal01
i.eb.hsebal01 −−help
i.eb.hsebal01 [−ac] netradiation=name soilheatflux=name aerodynresistance=name temperaturemeansealevel=name vapourpressureactual=name frictionvelocitystar=float [row_wet_pixel=float] [column_wet_pixel=float] [row_dry_pixel=float] [column_dry_pixel=float] output=name [−−overwrite] [−−help] [−−verbose] [−−quiet] [−−ui]

Flags:

−a

Automatic wet/dry pixel (careful!)

−c

Dry/Wet pixels coordinates are in image projection, not row/col

−−overwrite

Allow output files to overwrite existing files

−−help

Print usage summary

−−verbose

Verbose module output

−−quiet

Quiet module output

−−ui

Force launching GUI dialog

Parameters:

netradiation=name [required]

Name of instantaneous net radiation raster map [W/m2]

soilheatflux=name [required]

Name of instantaneous soil heat flux raster map [W/m2]

aerodynresistance=name [required]

Name of aerodynamic resistance to heat momentum raster map [s/m]

temperaturemeansealevel=name [required]

Name of altitude corrected surface temperature raster map [K]

vapourpressureactual=name [required]

Name of the actual vapour pressure (e_act) map [KPa]

frictionvelocitystar=float [required]

Value of the height independent friction velocity (u*) [m/s]
Default: 0.32407

row_wet_pixel=float

Row value of the wet pixel

column_wet_pixel=float

Column value of the wet pixel

row_dry_pixel=float

Row value of the dry pixel

column_dry_pixel=float

Column value of the dry pixel

output=name [required]

Name for output sensible heat flux raster map [W/m2]

DESCRIPTION

i.eb.hsebal01 will calculate the sensible heat flux map (h0), given both maps of Net Radiation and soil Heat flux (Rn, g0) at instantaneous time, the surface roughness (z0m), a map of the altitude corrected temperature (t0dem), a point data of the frictional velocity (u*), a value of actual vapour pressure (ea[KPa]) and the (x,y) pairs for wet and dry pixels. Full process will need those:

	•		i.vi, i.albedo, r.latlong, i.emissivity
	•		i.evapo.potrad (GRASS Addon)
	•		i.eb.netrad, i.eb.soilheatflux, i.eb.hsebal01
	•		i.eb.evapfr, i.eb.eta

(for time integration: i.evapo.time_integration)

i.eb.hsebal01 performs the computation of sensible heat flux [W/m2] after Bastiaanssen, 1995 in [1], used in this form in 2001 by [2]. Implemented in this code in [3].

NOTES

	•		z0m can be alculated by i.eb.z0m or i.eb.z0m0 (GRASS Addons).
	•		ea can be calculated with standard meteorological data.

eoTmin=0.6108*EXP(17.27*Tmin/(Tmin+237.3))
eoTmax=0.6108*EXP(17.27*Tmax/(Tmax+237.3))
ea=(RH/100)/((eoTmin+eoTmax)/2)

•

t0dem = surface temperature + (altitude * 0.627 / 100)

REFERENCES

[1] Bastiaanssen, W.G.M., 1995. Estimation of Land surface parameters by remote sensing under clear−sky conditions. PhD thesis, Wageningen University, Wageningen, The Netherlands. (PDF)

[2] Chemin Y., Alexandridis T.A., 2001. Improving spatial resolution of ET seasonal for irrigated rice in Zhanghe, China. Asian Journal of Geoinformatics. 5(1):3−11,2004.

[3] Alexandridis T.K., Cherif I., Chemin Y., Silleos N.G., Stavrinos E., Zalidis G.C. Integrated methodology for estimating water use in Mediterranean agricultural areas. Remote Sensing. 2009, 1, 445−465. (PDF)

[4] Chemin, Y., 2012. A Distributed Benchmarking Framework for Actual ET Models, in: Irmak, A. (Ed.), Evapotranspiration − Remote Sensing and Modeling. InTech. (PDF)

SEE ALSO

i.eb.soilheatflux, i.eb.evapfr

AUTHOR

Yann Chemin, International Rice Research Institute, Los Banos, The Philippines.

Contact: Yann Chemin

SOURCE CODE

Available at: i.eb.hsebal01 source code (history)

Latest change: Wednesday Nov 27 22:53:26 2024 in commit: b90ce69e88409469369ec1edb86fde8ec822af8b

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